The present invention relates to intake valve systems for multi-valve engines, and more particularly to methods and apparatus for enhancing air-fuel mixing and charge motion in the combustion chamber of the engine.
It is a common goal with vehicle manufacturers today to provide engine and combustion systems which improve fuel economy and, at the same time, reduce undesirable emissions. There are many systems which have been developed which accomplish one or more of these goals and achieve satisfactory results. Some of these systems include, for example, supplying prespecified amounts of fuel and air at certain times in the combustion cycle of the engine, various combustion chamber configurations including shaped bowls in the piston head in order to secure desired air-fuel mixtures under various operating conditions, intake and exhaust valve mechanisms which create desired tumble and/or swirl patterns of air and air-fuel mixtures in the combustion chamber, and the like. Some of these systems are used in particular for spark ignited (SI) engines.
Charge motion in the combustion chamber is an important factor for generating turbulence which in turn enhances the burn rate in the engines. However, the tumble and/or swirl generation often comes at the expense of discharge coefficient, thus reducing the maximum power output of the engine.
In multi-valve camless engines or in multi-valve engines with valvetrains where either intake valve can be independently controlled or deactivated, alternating the operation of the intake valves can improve fuel economy and enhance combustion. However, accumulated and unburnt fuel in the closed port can have an undesirable effect on emissions.
Thus, there is a need for an engine combustion system which enhances air-fuel mixing and charge motion in the combustion, particularly in camless engines.
It is an object of the present invention to provide an improved combustion system for an engine. It is another object of the present invention to provide gas exchange between two intake ports in multi-valve engines. It is a further object of the present invention to provide a combustion system which secures high fuel efficiency and at the same time reduces undesirable emissions.
The present invention provides a system and apparatus for eliminating the build up of unburnt fuel in the closed intake port in multi-valve engines, such as camless engines or engines with valvetrains where either intake valve can be independently controlled or deactivated. In accordance with the present invention, a multi-valve engine is provided with at least two independently operated intake valves in each cylinder. A high swirl and tumble turbulence flow is provided in the combustion chamber by delaying or advancing the opening of one intake valve relative to the other. Each of the intake valves is operated by an electromechanical actuator which in turn is activated by the engine controller.
A diverter member or intake port wall is positioned in the air intake passageway between the two intake ports and valve members. A channel or passageway is provided in the diverter member in order to transfer fuel from the closed port to the open port.
The passageway preferably has a configuration with a certain curvature relative to the size of the inlet ports. Preferably, the radius of this curvature is about one-half the diameter of the inlet port. In addition, the passageway is symmetrical relative to the two inlet ports which allows flexibility of use between either inlet port. This is particularly important in camless engines and engines wherein either intake valve can be independently controlled or deactivated. Further, the entrances to the passageways are positioned a certain distance from the valve seats relative to the size of the inlet ports. Preferably, this distance is about one-quarter of the diameter of the inlet ports. Finally, the exit portions of the passageway are curved or angled in order to direct the flow passing through the passageway toward the opposite sides of the inlet ports.
The present invention has the flexibility to achieve the proper timing of the opening and closing of the intake valves to secure optimum combustion of the fuel under all operating conditions. The opening and closing of the intake valves is varied by the engine controller and is dependent on the engine speed and engine load. The present invention also provides optimum location, symmetry and configuration of the passageway between the inlet ports.
The passageway in the diverter member allows transfer of fuel from one port to the other in order to enhance the use and burning of the fuel and to reduce undesirable emissions.